W3C home > Mailing lists > Public > w3c-rdfcore-wg@w3.org > April 2002

Re: addressing requirements around daml:collection (rdfms-seq-representation)

From: Dan Connolly <connolly@w3.org>
Date: 22 Apr 2002 17:51:30 -0500
To: Pat Hayes <phayes@ai.uwf.edu>
Cc: Jos De_Roo <jos.deroo.jd@belgium.agfa.com>, Lynn Andrea Stein <las@olin.edu>, w3c-rdfcore-wg@w3.org
Message-Id: <1019515900.4818.1161.camel@dirk>
On Mon, 2002-04-22 at 17:35, Pat Hayes wrote:
> >[...]
> >
> >>  RDF/xml has special syntax for containers, but experience
> >>  trying to exploit it to come to intuitive conclusions
> >>  has exposed problems. Take the class above... say
> >>  Continent is the subject of that oneOf property.
> >>  If we know
> >>
> >>     ex:Bob daml:differentIndividualFrom ex:Eurasia.
> >>     ex:Bob daml:differentIndividualFrom ex:Africa.
> >>     ex:Bob daml:differentIndividualFrom ex:North_America.
> >>     ex:Bob daml:differentIndividualFrom ex:South_America.
> >>     ex:Bob daml:differentIndividualFrom ex:Australia.
> >>     ex:Bob daml:differentIndividualFrom ex:Antarctica.
> >>
> >>     ex:NotContinent daml:complementOf ex:Continent.
> >>
> >>  then we should be able to conclude
> >>
> >>     ex:Bob rdf:type ex:NotContinent.
> >>
> >>  Now this works perfectly well* when the oneOf claim
> >>  is spelled out long-hand using first/rest/nil.
> 
> [To Dan:]
> Well, that isn't clear.

Sigh... I should have known better than to make that claim
without working out the details...

> After all, it is RDF-legal to add some other 
> rest/first/rest chains to the same bnodes,

Well, first and rest are UniqueProperties.

i.e. if

	:x ont:first :y.
and
	:x ont:first :z.
then
	:y ont:equivalentTo :z.

So if you add other first/rest chains, you claim
the relevant gizmos denote the same thing. If that's
not the case, you've contradicted yourself.

> so the daml:list is just 
> as dependent on a closed-world assumption

I don't see any closed world reasoning in saying
that first/rest are functional/unique properties.

> as the RDF container syntax 
> would be in this context. I bet that your (and Jos) code would break, 
> or act unpredictably, if given a branching daml:list.

Well, 'unpredictably' is probably a reasonable way to
characterize the behaviour of a prover when given
inconsistent input. But I don't see why this
case is special in that respect.


-- 
Dan Connolly, W3C http://www.w3.org/People/Connolly/
Received on Monday, 22 April 2002 18:51:42 EDT

This archive was generated by hypermail pre-2.1.9 : Wednesday, 3 September 2003 09:47:35 EDT